1. Field of the Invention
The present invention relates to a method and apparatus for synchronous reproduction of main contents recorded on an interactive recording medium and additional contents therefor.
2. Description of the Related Art
High-density optical disks capable of storing large amounts of high-quality digital video/audio data have been widely used. The DVD (digital versatile disk) is one example of these high-density optical disks.
The DVD includes a data stream recording area in which digital video contents are stored and a navigation data recording area in which navigation data required for playback control of the video contents is stored.
When a DVD is loaded into a DVD reproducing apparatus, the DVD reproducing apparatus first reads the navigation data recorded in the navigation data recording area and stores the navigation data in an internal memory. The DVD reproducing apparatus then reproduces the video contents recorded in the data stream recording area using the navigation data.
In the meantime, the development of new interactive DVDs is being progressing. Unlike the DVD, the interactive DVD (hereinafter referred to as iDVD) contains additional contents data related to the main A/V data recorded thereon.
The additional contents (also called ENAV data in iDVDs) generally comprises a document part including markup languages (e.g., XHTML or SMIL) and cascading style sheets and a data part including JPEG or PNG images, AC-3, MPEG, DTS, or SDDS audio data, MNG animation, and/or text.
Various additional contents pertaining to main A/V data recorded on a recording medium provides users more flexibility and thus allows the users to enjoy the main AN contents more effectively.
The additional contents pertaining to the main contents recorded on a recording medium need to be the latest information. It may be possible to provide the additional contents through a broadband communications network (e.g., the Internet) as well as through the recording medium. An iDVD reproducing apparatus, therefore, is required to be able to play the main A/V data recorded thereon in synchronization with a part of additional contents provided from an external source if the part is intended for synchronized reproduction.